In many applications it is desirable to create optical assemblies that are stable, easy to fabricate, and are capable of operating in harsh chemical and thermal environments. For example, it is desirable to have optical assemblies that can operate in the presence of alkali-metal vapor and can be heated up to 200° C. without alignment changes. It is further desirable to have optical assemblies that are vacuum-compatible and have low outgassing properties. FIG. 1 depicts a prior art multi-pass cell 100. Multi-pass cell 100 can be hermetically sealed and filled with alkali-metal vapor 102. The multi-pass cell 100 can be made using two cylindrical mirrors 130 and 140. One mirror (generally a front mirror 130) can have a hole or aperture 132 at a center of the mirror in order to allow for the entrance and exit of beams (such as laser beam 195 from lasing source 190). The second mirror can include back mirror 140. Curvature axes of the two mirrors 130 and 140 can be oriented at a specific angle relative to each other, and a distance between the mirrors 130 and 140 can be accurately set to allow for a multi-pass beam pattern between the mirrors 130. It can be advantageous to place both mirrors 130 and 140 inside a vacuum-sealed enclosure to eliminate losses associated with light passing through optical windows.
However, consequences of using alkali-metal vapor over the above-described temperature range can largely preclude the use of adhesives to mount optical elements 130 and 140. Moreover, while various optical contacting techniques can be used to mount optical elements 130 and 140, such optical contacting techniques can require atomic level polishing and flatness, and so can be expensive to implement.